Hyperbolic cross flow cooling tower with basins and fill integrated into shell

ABSTRACT

A fireproof, hyperbolic, natural draft, crossflow water cooling tower having two story fill assembly structure between respective concrete hot water distribution and cold water basins within the tower shell and integral therewith adjacent the air inlet of the shell. Stainless steel fill and eliminator supports suspended from the distribution and basin units carry transversely threequarter wave asbestos cement board fill members and transversely full wave eliminator bars respectively cut from corrugated sheets. The fill members are disposed on edge with the longitudinal length thereof parallel to the air flow through each fill assembly structure while the eliminator bars lie in flat, generally horizontal disposition with the longitudinal axes thereof slightly tilted for drainage of the bars and located perpendicular to the path of travel of air through respective fill assembly structures.

[ Oct. 9, 1973 HYPERBOLIC CROSS FLOW COOLING TOWER WITH BASINS AND FILL INTEGRATED INTO SHELL [75] Inventor: Homer E. Fordyce, Kansas City,

[73] Assignee: The Marley Company, Kansas City,

22 Filed: Sept.11, 1969 21 Appl. No.: 857,134

[52] US. Cl. 261/111, 261/DlG, ll [51] Int. Cl B0lf 3/04 ['58] Field of Search ..261/108112, DIG. ll

[56] References Cited UNITED'STATES PATENTS 821,561 5/1906 Wheeler et al. 261/DIG. 11 3,322,409 5/1967 Reed 261/DIG 11 3,411,758 11/1968 Edmondson 261/DIG 11 3,333,835 8/1967 De Flon 26l/D1G 11 3,389,895 6/1968 De Flon 261/DIG. 11 2,512,271 6/1950 Green 261/111 3,115,534 12/1963 Bonner... 261/110 FOREIGN PATENTS OR APPLICATIONS 998,822 7/1965 Great Britain 26l/DIG. 11 528,938 11/1940 Great Britain 261/DIG. 11

OTHER PUBLICATIONS McKelvey and Brooke, The IndustrialCooling Tower,

' p. 145; Elsevier Publishing Co., 1959 McKelvey and Brooke, The Industrial Cooling Tower, pp. 67, 132, 137, 271, 290, 357, 358; Elsevier Publishing Co., 1959.

Rish and Steel, Design and Selection of Hyperbolic Cooling Towers', October, 1958; pp. 43-54.

Primary Examiner-Tim R. Miles Assistant Examiner-Steven I-I. Markowitz Attorney-Schmidt, Johnson, Hovey & Williams [5 7 ABSTRACT A fireproof, hyperbolic, natural draft, crossflow water cooling tower having two story fill assembly structure between respective concrete hot water distribution and cold water basins within the tower shell and integral therewith adjacent the air inlet of the shell. Stainless steel fill and eliminator supports suspended from the distribution and basin units carry transversely three-quarter wave asbestos cement board fill members and transversely full wave eliminator bars respectively cut from corrugated sheets. The fill members are disposed on edge with the longitudinal length thereof parallel to the air flow through each fill assembly structure while the eliminator bars lie in flat, generally horizontal disposition with the longitudinal axes thereof slightly tilted for drainage of the bars and located perpendicular to the path of travel of air through respective fill assembly structures.

6 Claims, 7 Drawing Figures SHEET 2 (IF 3 PATENTED 9 INVENTOR Homer E. Fomfyce 25 n I, 14 #Mw/ HTTORNEVS.

V particularly to a fireproof, hyperbolic, natural draft,

c ros'sflow water cooling tower wherein thefill structures "are'dispos'ed within the tower shell between hot water di'str'ibutionand cold water basin units integral withthetowershell. -By virtue "o'fthe unique integration oft'hei'basinsand-fill into th'e'towe'r shell, stacked, two story "fill -as's'e'rn blyiit'iu'tit'ur'e may be provided adjacent the'airinl't'ofthe shell'with thean'nular hotand cold water basins thereof a perform ing 1 the functions of sup- "plyinghotw'ater to cdrresponding fill assemblies. and

collectin'g 'thecold water gravitating'th'erefrom, as well as "reinforcing the botto'in section 'of the hyperbolic shell to "make possible construction of larger towers than heretoforefab'ricat'ed without-necessarily providing a ccSfreSpohHi'ngincrease in th'e "structural strength of the tower *sh'ell it'self adjacent the bottom portion thereof.

Water cooling towersf provided with'hyperbolic, natural dr'a ft sjtacls to induce 3 flow "of "air through the fill assembly o'f the towe'r have "been employed for many years,*particu1ar1 =in European countries where'power costs 'liave remained 'relat'ively'hig'h, 'by virtue of the fact-thatoperating expensesmadethe-cost of the shell feasible fr'd'in an overall economic standpoint. Hyperbolic, natural draft cooling towers have only -'recently found a *Signi fic'ant place in the "domestic market. Tower costs-'have' for t'h'e most' part fnad'e mec'hanical induced draft towers the "most efficient and "practical from an "overall cost'standpoint for'most industrial ap- 'plic-atio'ns. -"R'eeent trends in 'powerplants-though have changed the cost and feasibiIity l standards in that the extremely large-power plants 'now 'being constructed or contemplated require-volumes of cold water for cooling purposes many tiines that heretofore "needed for :tliese -a'pplications. Hyperbolic, natural draft cooling "towers have "been found-to be commerciallycompetitive and attractive for' large power plants where hundr'e'dsof t'housands'of-gallonsof water must" be handled per hou'r. Aspower plant desig'n has-goneabove the l,000-"'megawatt level, t-he required" size of the; hyper- 'bolic towrsn'eeded forplants'of these capacities has further-eiipan'ded.

Most or the early I hyperbolic, Y natural --draft cooling towers and es'pecially those built-in 'Europe were of -counter flo'w'desig'n. ln-this-type of unit, the fill assembly structurewas located within the lower part of the tower shell in disposition such that water sprayed downwar 'dly onto interseeting,"vertically spaced-grids gravitated toward the cold water basin in counterflow "relationship to air'pulled' in 'around the perimeter of the tower and-" caused to "move-upwardly toward the outlet of the fsh'ellby" the natural -"draft induced by the rela-' tively high' height' of the tower."However,-a-crossflow cooling tower-can-handle moreair foragiven shell sizethan the--qoumernowconcept. This is attributable to the lower resistance to air' fl'o'w'thi'ou'gh the fill assembly of a'crossflow tower ascompared with air resistance encountered in a counterflow tower. As a consequence, 'cro'ssflow towers-are less-expensive for handling the' sa'nfie volume of hot'waterIThe increased cost of'a cotinterflow design is"in-part traceable to the fact that'in a coiin'terflowtower it-is necessary to; provide space under the fill'asserri'bly' for air to come in from the outside for distribution across the bottom of the fill. The fill assembly must therefore bepositioned a sub stantial distance above .ground level to permit air'to enter the tower above the cold water basin an'dthen flow upwardly through the fill grids or racks. Very little water cooling takes place in this plenum areabelowthe fill assembly in a counterflow tower. Since in acounterflow design the water is falling vertically while the air flow is in direct opposition thereto, it is to be appreciated that the falling water has a tendency to create much greater resistance to the flowing air than is the case in a crossflow design wherein the-air is-flowing at essentially a 90 angle with respect to-the fallin'g water.

Furthermore, the extra space which must be provided under a counterflow fill in many cases necessitates a higher pumping head than with a crossflowdesign and in hyperbolic, natural draft cooling towers of large capacity, the pumping head is proportionately increased.

Although the initial hyperbolic, natural draft cooling towers were of counterflow design as noted, more recent hyperbolic towers have been constructed incrossflow form because of the greater efficiency in comparison with the cost thereof over the counterflow type. In this instance, the fill assembly structure has been located around the perimeter of the tower shell with-the tower thereby serving to induce crossfiow movement of air through the annular fill structure surrounding the tower thus obviating the necessity of providing'mechanical means for moving air through the fill'structure.

The water volumes required for high megawatt power plants now under construction or being planned necessitate very large towers which for example "may be 500 feet or higher in height and have a corresponding largediameter at the base. In view of the desirability of having from 800 to 1,000 feet per minute air discharge velocity from the shell to cool water with'maximumefficiency, it has heretofore been found necessary in crossflow towers to position the fill assembly structure outside of the shell around the perimeter thereof with an annular hot water distributor being located in overlying relationship to a cold water collection basin beneath the annular fill. Because water tends to 'move inwardly in the direction of air flow during gravitation through the fill, the hot water basin normally has been of greater diameterthan the cold water collection basin to. provide compensation for this natural drawback of the water. As a result, the hot water-basin has been located some distance from the proximalperipheral surface of the tower shell. The annular space left'between the hot water basin and the shell'has in part been occasioned by the hyperbolic configuration of thetower shell itself. In order to close the annularspace between the inner edge of the hot waterdistributor and the tower shell, it has been necessary to provide an annular, frustoconical canopy between the tower shell and the hot water basin to prevent flow of air into the interior of the tower other'than throughthe fill structure inlet. As the size of the hyperbolic-tower is increased though, the annular canopy between the shell-and hot water basin must be increased to a point where it is no longer economically feasible to provide a shroud of'a size sufficient to close the annular space and also withstand snow and wind loads thereon.

Furthermore, the fill structure employed in crossflow hyperbolic, natural draft cooling'towers has for the most part been of conventional wood slat construction with the hot water distributor also being fabricated of wood because of its good corrosion resistance characteristics. Only the cold water collection basin has been of concrete fabrication. As a result, a considerable fire hazard has been presented by the wooden hot water distributor and fill units particularly in those instances where at least a part of the fill is not loaded with water, as for example in cold weather operation wherein a larger proportion of hot water may be directed to one side of the tower to prevent icing thereof or where adequate cooling of the water is obtained under operating conditions where water is not passed over the entire circumferentially extending area of the fill assembly.

The primary object of the present invention is to provide a crossflow, hyperbolic, natural draft cooling tower wherein two story basin and fill assembly structure is integrated into the shell to significantly increase the water cooling capacity of the tower without enlarging the space taken up by the tower while at the same time providing completely fireproof construction.

A further important object of the invention is to provide a hyperbolic, natural draft, crossflow cooling tower with basins and fill integrated into the shell of the tower wherein the two story fill is disposed in two annular stacked layers for maximum efficiency without increasing the overall size of the tower or significantly impeding air flow through the shell, all at-a cost which is competitive with other types of equipment in light of the capacity of the tower and the space occupied thereby.

In this connection, it is a further important object of the invention to provide a crossflow, hyperbolic, natural draft cooling tower wherein the annular hot water distribution basins and at least the upper cold water basin of the two story fill units are of concrete and integral with the tower shell to not only provide an integrated structure but also serving to greatly stiffen the tower shell in the base area thereof where the most strength is required.

Another important object of the invention is to provide a hyperbolic, crossflow cooling tower operating on the natural draft principal wherein the fill assemblies are made up of a series of stainless steel grid supports suspended from the concrete basin structure thereabove and carrying a series of asbestos cement board fill members positioned on edge with the longitudinal axes thereof parallel with the air flow through the fill structures so as to assure efficient airliquid contact within the fill while at the same time providing a completely fireproof tower which is resistant to physical deterioration.

A still further important object of the invention is to provide a crossflow, hyperbolic, natural draft cooling tower wherein ice control is readily accomplished by the simple expedient of controlling the hot water so that an excess is permitted to flow over the intake side of the fill, either around the entire perimeter thereof, or in those areas of the tower which tend to ice because of a particular prevailing wind condition. I

Since structural members within the path of air flow through a cooling tower increase the static pressure drop, it is an important object of the invention to provide a cooling tower as described wherein the corrosion resistant wire fill grids and the asbestos cement board fill members as well as eliminators of the same construction provide minimum impedance to air flow by virtue of the disposition of all fill elements in locations such that the longitudinal axes thereof are parallel with the air flow in the case of the fill members or have side margins facing the air flow path insofar as the eliminators are concerned, thus assuring maximum performance of the tower under widely varying operating conditions.

Other objects and features of the present invention will become apparent or be described in greater detail as the following description progresses.

In the drawings:

FIG. 1 is a side elevational view of a hyperbolic, natural draft, crossflow cooling tower constructed in accordance with the preferred concepts of the present invention, with the lower left-hand part of the tower being broken away and in section to reveal the position of the fill assembly structure within the shell of the tower, as well as one part of piping for conveying hot water to the distribution basins as well as toreturn cold water to the source of use thereof;

FIG. 2 is a fragmentary elevational view taken sub- 7 stantially on the line 2-2 of FIG. 1 in looking in the direction of the arrow;

FIG. 3 is an essentially schematic, fragmentary plan view showing the individual fill sections of the upper fill assembly structure and illustrating the normal relative positions of the sections to provide compensation for the annular area occupied thereby within the confines of the cooling tower shell as illustrated in FIG. 1;

FIG. 4 is an enlarged fragmentary vertical crosssectional view of the lower left-hand corner of the cooling tower as illustrated in FIG. 1 with the exception that the supply and return pipes are not illustrated for clarity;

FIG. 5 is a fragmentary enlarged generally vertical cross-sectional view illustrating the eliminator structure suspended from the uppermost hot water basin as depicted in FIG. 4; 7

FIG. 6 is an enlarged fragmentary cross-sectional view on the line 6-6 of FIG. 7 of one of the sections of a fill assembly of the cooling tower and showing the way in which the corrosion resistant wire grids are suspended from the basin thereabove while the asbestos cement board fill members are located in essentially upright disposition with the longitudinal axes thereof parallel to the air flow through the fill structure; and

FIG. 7 is a vertical cross-sectional view taken substantially on the line 7-7 of FIG. 6.

The hyperbolic, crossflow, natural draft cooling tower 10 illustrated in the drawings is especially adapted for large capacity jobs, as for example where it is necessary to cool hot water and return it to the condensers of a power plant exceeding 1,000 megawatts in output. In this instance, a typical tower shell 12 should have a total effective height of 500 feet or more thus resulting in a base diameter of about 450 feet, a top diameter of almost 350 feet, and a throat diameter approaching 300 feet or more. Shell 12 is fabricated of reinforced concrete carried by an annular array of X- defining reinforced concrete trusses 14 supported by an annular concrete footing. The circular concrete floor 16 of tower extends to the perimeter of trusses 14 and is provided with an inwardly inclined, annular upright wall 18 above footing 21 which cooperates with floor 16 to define a lower cold water basin 20. The trusses 14 are preferably poured integral with the wall 18 to impart increased rigidity and strength to the lower part of tower 10.

X-shaped trusses 14 are made up of poured in place upper and lower upright and inverted V-shaped support members and 17 as shown schematically in FIG. 1 which are joined at their apexes by connectors 19. The members 15 and 17 arecooperable to define upper and lower openings respectively which present an annular air inlet 24 for the hyperbolic shell 12. The top of shell 12 is open to present an air discharge outlet. The lower annular marginal portion 12a of shell 12 directly above the air inlet 24 thereof defined by trusses l4 and rigidly secured to the interior surface of shell 12 by a reinforcing steel and the like, serves as the outer supportfor an annular horizontal concrete floor 26 which is provided with an integral upright circular wall 28 spaced inwardly from shellportion 12a. A series of upright, horizontally spaced structural supports 30 carried by footing 23 within the interior of tower 10 and directly underlying the inner circular margin of floor 26 in direct supporting relationship thereto, are located in an annular pattern within the interior of shell'12 as indicated in FIGS. 1 and 4. The portion 12a of shell 12 and inner circular wall 28 cooperate with floor 26 to' present an upper annular hot water basin 32.

A series of longitudinally arcuate, upright reinforced concrete ring segments 34 poured against the upright margins ofadjacent connectors 19 forming a part of X- shaped trusses 14 at the zone of merger of the inclined legs thereof as illustrated schematically in FIG. 1, have reinforcing rods and the like common with trusses 14 to provide an integral joinder of ring segments 34 to respective trusses 14. The horizontal, annular reinforced concrete floor 36 joined to the lower margins of ring segments 34 and connectors 19 as well as members 17 has an inner circular margin 36a which is vertically aligned with the inner margin 26a of .floor 26. The floor 36 is also carried by the inner, upright structural sup ports 30 while an inner upright reinforced concrete wall 38 on floor 36 is disposed in alignment with wall a part of basin 42 are provided with a series of openings therethrough which may or may not have distribution nozzles therein, for permitting hot water from respective basins to flow downwardly onto corresponding fill assembly structures 48 and 50. The section 360 of floor c as indicated schematically in FIG. 3. Each section 28 at the inner margin 36a of floor 36. An intermedi- 46 be positioned in alignment with corresponding structural supports 30 radially of shell 12.

Fill assembly structures 48 and 50.0f annular extent and located between upper hot water basin 32 and the lower cold water basin 44 as well as hot water basin 42 and the lower cold water basin 20 respectively, are.

made up of a series of corrosion resistant wire grids which support a series of asbestos cement board fill members 52.

Although not illustrated specifically in the drawings,

. it is to be understood that the floor 26 of hot water basin 32 as well as the section 36b of floor 36 defining 48a, b and c is made up of a number of vertically spaced, transversely S-shaped, three-quarter wave asbe'stos cement board fill members 52 cut from corrugated sheets and positioned with their longitudinal axes in radial disposition relative to the axis of shell 12 and thereby in parallel relationship to the path of travel of air flowing into tower 10 through the air inlet 24 thereof. in order to provide compensation for the tendency of water gravitating from corresponding hot water distribution basins 32 and 42 to draw back in the direction of air flow as the bottom of respective fill assembly structures 48 and 50 are approached, the outer annular faces of structures 48 and 50 are stepped back asthe cold water basins therebelow are approached as is evident from FIGS. 1 and 4. Thus, referring to the uppe'rmost fill sections 48a, b and-c of fill assembly structure 48 immediately belowthe lower face of wall 26, an outer stainless steel grid 54 is suspended from the wall 26 while a longer stainless steel grid 56 is carried beneath wall 26 in inwardly spaced relationship from the proximal grid 54. As shown in FIGS. 6 and 7, each of the grids has a series of upright elements 58 crossed by and integral with the.horizontal,'vertically spaced fill membersupporting components60 which are spaced apart a vertical distance greater than the effective vertical height of corresponding fill members 52 carried thereby. Adjacent'pairs of elements 58 are brought together and rewound upon themselves to present eyes 58a forengagement with corresponding hooks 62 embedded in the lower part of floor 26.

The fill members 52 of the uppermost section 48b are carried by wire grids 64 and 66 of successively greater length while inner grids 68 and 70 of equal length support the fill members 52 of fill section 48c. Three additional grids 72, 74 and 76 spaced radially inwardly of grid 70 support the fill members 52 of sections 48a, b and c below the upper sections which are successively stepped inwardly as is apparent from FIG. 4.

Returning to FIGS. 6 and 7, it is to be noted that the three-quarter wave asbestos cement board fill members 52 are of greater width than the spacing between proximal elements 58 and are located on corresponding components 60 in disposition such that one upper transversely arcuate segment 52a thereof extends in a somewhat vertical direction transversely of the grids 54 and 56 whereas each integral, arcuate segment 52b is in somewhat horizontal disposition. This preferred relationship of segments 52a and 52b with respect to water gravitating from basin 32 onto corresponding fill members, is assured by proper spacing of elements 58 relative to the effective width of each fill member 52. The spacing between elements 58 is carefully designed so that rather than sit directly upright on edge, the till members 52 lie slightly 'on their sides so as to present the generally horizontal area defined by sections 52b serving to act as break-up or splash surfaces as well as the vertical segments 52a which operate as essentially film cooling surfaces.

In addition, the fill members 52 of each section 480, b and c are located in every other horizontal space defined by elements 58 but are vertically offset with respect to adjacent fill members 52 therebelow and immediately above so that the water directed onto sections 48a, b and c from hot water basin 32 must follow a circuitous or serpentine path before reaching cold water collection basin 54 therebelow. The fill members 52 are preferably fabricated from conventional corrugated asbestos cement board of the 42 inch wide, 4.2 inch wave, 6 or 8 foot long type which is severed longitudinally of the corrugations to provide the transversely three-quarter wave shape shown best in FIG. 7.

Adjacent fill segments 48a are in vertically stepped back relationship viewing FIG. 4, a distance approximately equal to one-half the length of corresponding asbestos cement board fill members 52. Compensation is thus provided for the tendency of the water gravitating through fill assembly 48 to draw back in the direction of air travel and thus assuring that substantially all of the fill stays wet for most efficient cooling with a minimum of contact surfaces being required since the rear face of each fill assembly structure 48 is also stepped in a complemental manner to the front face of a respective fill.

As indicated in FIG. 3, the fill sections 48a, 48b and 48c are located generally radially of shell 12 and therefore each section is in slightly greater spaced relationship at the inlet ends thereof than is the case at the inner extremities of the same.

A drift eliminator 78 is provided for each of the fill assembly structures 48 and 50 to remove droplets of water entrained in the air emerging from the rear faces of corresponding fill structures 48 and 50. Each eliminator 78'is made up of a plurality of vertical, horizontally spaced eliminator bar support grid units 80 of stainless steel. The upright horizontally spaced wire elements 82 and 84 of each grid 80 are joined by an upper inclined section 84a of each element 8 4. Grid units 80 are preferably suspended from J-shaped hooks 85 embedded in the vertical inner face of wall 28 in the case of the upper eliminator 78, or the lower surface of wall 36 inboard of divider wall 40 with respect to the lower drift eliminator 78. The horizontal, vertically spaced support elements 86 integral with elements 82 and 84 respectively serve as means for carrying a series of vertically aligned, transversely arcuate generally horizontally, drift eliminator bars 88 of asbestos cement board which are tilted slightly longitudinally thereof for drainage. Each bar 88 is preferably cut from conventional 42 inch wide, 177 mm wave asbestos cement corrugated boards 6 or 8 feet long so that each bar 88 is of transversely full wave shape to effect efficient scrubbing of air passing thereacross while at the same time possessed with sufficient inherent structural strength to span a considerable horizontal space between adjacent units 80. Each of the drift eliminators 78 extends downwardly to a sufficient extent to overlap the entire upright rear face of corresponding fill assemblies 48 and 50. The structural supports and 46 serve to stabilize the drift eliminators 78 as shown in FIGS. 4 by virtue of the fact that the inner upright elements 82 of each grid 80 rest againstthe innermost vertical surface of corresponding structural supports. Although shown in upright disposition, it is to be under stood that the drift eliminators 78 may be inclined in a direction complemental to the inclined inner faces of fill structures 48 and 50, if desired. Similarly, intermediate, horizontal, intermediate concrete support bars for grids 56 and 64-74 may be provided if desired where the vertical length of the grids is such as to present a problem of the amount of water and fill member loading that may be safely placed thereon.

One or more hot water supply pipes 90 and 92 communicate with the basins 32 and 42 respectively through conventional flume structure as shown in FIGS. 1 and 2 while one or more cold water return pipes 94 and 96 also lead from basins 20 and '44 to a point of use of the water.

In the operation of tower 10, hot water to be cooled is introduced into distribution basins 32 and 42 via supply pipes 90 and 92 whereupon the water is permitted to gravitate through the orifices in corresponding floors 26 and 36b onto the upper faces of sections 48a, 1; and c of the fill assembly structures 48 and 50 therebelow. impingement of the hot water against fill members 52 causes the water to be broken up to a certain extent while a part of the water forms a film on opposed surfaces of segments 52a and 52b for cooling thereby as air is pulled inwardly through inlet 24 and caused to move essentially horizontally through fill assembly structures 48 and 50 by virtue of the natural draft induced by shell 12 of tower 10. Any droplets of water.

entrained in the air as it emerges from the inner faces of fill assembly structures 48 and 50 is removed from the air by the scrubbing action produced by eliminator bars 88 of drift eliminators 78. The transversely ar'cuate shape of the bars 88 imparts some turbulence to the air to effectively remove droplets of water from the hot air without producing a deleterious static pressure drop.

In designing a hyperbolic, natural draft cooling tower of optimum characteristics from an operational as well as economic standpoint, it is necessary to determine the most efficient interrelationship of stack height and diameter, fill volume and total air inlet area thereof which is capable of handling the amount of water to be cooled from the high temperature encountered to the low temperature required for a particular installation, and taking into account not only the cost of the tower itself but also the operating costs thereof. Studies have shown that when the factors above are properly balanced, the hot air discharge velocity from the top of the stack will be approximately within the range of 800 to l,000 feet per minute. A velocity of this magnitude can be obtained with an economically sized tower shell only when the dynamic pressure losses and resistance to flow of air in the shell are not excessive.

A hyperbolic tower having two story integrated basin and fill structure as described above uniquely meets the desired design requirements of permitting construction of a shell of an economical size for the 'rated capacity thereof wherein a hot air discharge velocity of a preferred value may be obtained by virtue of the fact that the fill does not impair air flow therethrough to-an excessive extent while at the same time providing capacity for coolinga relatively large volume of water on a gallon per minute basis because of the double story nature of the fill.

In addition, the use of elongated fill members 52 which are positioned with their longitudinal axes in parallel relationship to the cross flowing air moving through corresponding fill assembly structures 48 and 50, produces efficient cooling of the water without adversely affecting air velocity through the fill itself. All of the above advantages are obtained without the necessity of disposing the till assembly around the outside perimeter of the tower as has heretofore been required, and at the same time producing a completely fireproof construction. The use of concrete for fabricating the shell as well as the distribution and collection basins is an advantage not only from the standpoint of being flameproof, but also because of the structural strength of this material when suitably reinforced. Stainless steel fill and eliminator grids as well as asbestos cement board fill members and eliminator bars permits elimination of all materials from the tower which could burn.

In past crossflow, hyperbolic, natural draft towers where the fill structure was disposed around the periphery of the tower, it was necessary to provide inlet louvers around the fill to contain water gravitating through the fill structures and avoid excessive splash out from the tower. Although concrete is generally considered a suitable material for constructing cooling towers, especially those of the hyperbolic natural draft type, the

construction of inlet louvers of concrete would excessively add to the cost of the tower. However, in the present tower this problem has been avoided by virtue of extension of the cold water basin outwardly to the circular margin of the base of the shell 12 thus eliminating the need for inlet louvers because of the stepped back configuration of the fill structures 48 and 50 with respect to the frustoconical base portion of shell 32. Ice control in this connection may be readily accomplished by providing excessive water on the intake face of each fill assembly structure 48 and 50. Similarly, added water may be directed to that part of the tower which tends to ice under a given wind condition, so long as radial dividers are provided for basins 32 and 42 to permit selective direction of water to circumferentially spaced sections around the base of the shell 12.

Not only does the shell 12 and support trusses M serve to assist in the support of the upper and lower water distribution basins as well as the upper cold water collection basin, but these annular concrete'structural components also in turn greatly stiffen the shell. This is particularly important in a tower of the size contemplated by this design. Additionally, the hot water distribution basins 32 and 42 serve as a support for the fill assembly structures 48 and 50 as well as the eliminators 78 and provide a fiume to distribute the hot water around the tower. The hot water basins can thereby be designed for most practical water flows under varying use conditions.

Having thus described the invention, what is claimed as new and desired to be secured by Letters Patent is:

1. A cooling tower comprising: an upright, natural draft shell provided with an open top defining an air discharge outlet and an air inlet around the perimeter of the shell at the bottom thereof; upper and lower, vertically spaced cold water basins underlying at least the interior portion of the shell proximal to said air inlet thereof; upper and lower annular hot water distribution means within the shell above the upper and lower cold water basins respectively; and fill assembly structure within the shell between each hot water distribution means and the cold water basin therebelow in positions for movement of air therethrough from the air inlet toward the discharge outlet in crossflowing relationship to hot water gravitating through corresponding fill assembly structures from the hot water distribution thereabove toward the underlying cold water basin,.

- provided an upright divider wall on said floor intermediate the opposed annular margins thereof, and an inner upright wall on the floor in spaced relationship from said divider wall.

4. A cooling tower as set forth in claim 1, wherein said upper hot water distribution means and the upper cold water basin therebelow are offset inwardly of the shell toward the vertical axis thereof with respect to the lower hot water distribution means and the lower cold water basin below the same.

5. A cooling tower as set forth in claim 1, wherein at least said hot water distribution means and the upper cold water basin are integral with the shell.

6. A cooling tower as set forth in claim 1, wherein said shell, the hotwater distribution means and said cold water basins are of concrete. 

1. A cooling tower comprising: an upright, natural draft shell provided with an open top defining an air discharge outlet and an air inlet around the perimeter of the shell at the bottom thereof; upper and lower, vertically spaced cold water basins underlying at least the interior portion of the shell proximal to said air inlet thereof; upper and lower annular hot water distribution means within the shell above the upper and lower cold water basins respectively; and fill assembly structure within the shell between each hot water distribution means and the cold water basin therebelow in positions for movement of air therethrough from the air inlet toward the discharge outlet in crossflowing relationship to hot water gravitating through corresponding fill assembly structures from the hot water distribution thereabove toward the underlying cold water basin, a part of said shell being configured to define the outer, upright, annular wall portion of each of said hot water distribution means, the lower hot water distribution means being located at essentially the same horizontal level as the upper cold water basin.
 2. A cooling tower as set forth in claim 1, wherein is provided a common annular floor defining the bottom of said lower hot water distribution means and the bottom of the upper cold water basin respectively.
 3. A cooling tower as set forth in claim 2, wherein is provided an upright divider wall on said floor intermediate the opposed annular margins thereof, and an inner upright wall on the floor in spaced relationship from said divider wall.
 4. A cooling tower as set forth in claim 1, wherein said upper hot water distribution means and the upper cold water basin therebelow are offset inwardly of the shell toward the vertical axis thereof with respect to the lower hot water distribution means and the lower cold water basin below the same.
 5. A cooling tower as set forth in claim 1, wherein at least said hot water distribution means and the upper cold water basin are integral with the shell.
 6. A cooling tower as set forth in claim 1, wherein said shell, the hot water distribution means and said cold water basins are of concrete. 